1. Field of the Disclosure
The present disclosure relates to systems for forming tubular strings for use in a wellbore.
2. Description of the Related Art
Threaded connections are a prevalent method to join two or more members such as pipe sections, drill strings, such as drill collars, drill bit bushings, centralizers, shock collars, directional tools, casing, tubing, line pipe, flow lines and subsurface production tools. Make-up or connection of such threaded joints can require very high torque. Because the thread faces of such joints can be subjected to high bearing stresses as well as harsh mounting conditions there is a risk that these loads will gall and damage the threaded joint.
One method of protecting joints from damage such as galling is to apply an anti-seize compound between the mating threads. Such a compound inhibits the “welding” that may otherwise occur under the pressures and heat incurred during proper make-up. Exemplary compounds usually contain finely divided metal powder such as zinc or lead and sometimes other ingredients such as active sulfur. Experience has shown that these compounds may degrade over time or under the influence of the extreme operating conditions, which can lead to loss of their anti-galling properties. Furthermore, many of these compounds are now classified as hazardous substances because of their high metal particle content.
U.S. Pat. No. 6,371,224 (the '224 patent) reports that Italian Patent 980421 to Baryshnikov et al. describes a threaded spacer which is intended to replace conventional thread compounds. Referring now to FIG. 1, there is isometrically illustrated a threaded spacer generally representative of the devices described in the '224 patent and Italian Patent 980421. The '224 patent explains that “the particular threaded spacer [10] disclosed is composed of a conical section [12] having a flange [14] at its open, larger end [16]. Cooperating helical grooves [18] are formed in the inside and outside surfaces of the conical section wall [20] such that the conical wall, as a whole, is undulating in cross section.” The '224 patent further explains that the conical section 12 of the spacer 10 can be received between mating grooves of adjacent drill pipe sections, while the flange will fill the annular space defined between the shoulders of adjacent pipe sections. Thereafter, the '224 patent describes “a new process . . . for making threaded spacers of the type shown in Italian Patent 980421.”
During use, the described prior art thread saving device is subjected to relatively high torques, high contact forces and high friction forces. Partly because this prior art thread saving device may be very thin, perhaps 0.25 millimeters thick in the conical areas, the operating loads can deform or crush the prior art thread saving device to a point where the prior art thread saving device cannot be readily removed from either the male end or the female end of the pipe joint. In such cases, it can be a time consuming process to break apart or extract the prior art thread saving device from the joint, which usually is often required, e.g., after each run downhole for the purpose of crack inspection.
The present disclosure addresses these and other drawbacks of this prior art thread saving device.